Field of the Invention
The present invention relates to a supporting mechanism for supporting a load of various articles and the like and, more particularly, to a load supporting mechanism that supports a target article at a desirable position in a displaceable manner.
Description of the Related Art
There have been proposed various types of supporting mechanism for the purpose of supporting an article, such as a monitor device of a computer or a TV, a top plate of an OA desk or a working table, a heavy article, or the like, at a desirable height position in an elevating/lowering manner. For example, there is known a monitor device supporting mechanism capable of vertically moving a monitor device and positioning the same with a fixed supporting force (for example, see Patent Document 1 [Jpn. Pat. Appln. Laid-Open Publication No. 2002-303304]).
The monitor device supporting mechanism described in Patent Document 1 has at least one cam, at least one cam follower member, an energy storage member, and a movable body to which the monitor device is mounted. In the monitor device supporting mechanism, when the movable body is moved along a fixed base, a spring is compressed/extended to increase/decrease elastic energy stored in the spring. A spring force of the spring is converted into a reaction force against the cam follower member from a cam surface. The reaction force includes a first component directed in a moving direction of the movable body and a second component directed in a direction substantially perpendicular to the first component. A shape of the cam is designed such that even if the second component is increased/decreased by the compression/extension of the spring, the first component directed to its moving direction is maintained so as to allow a substantially constant supporting force to act on the movable body and monitor device.
According to Patent Document 1, a force that biases the movable object and monitor device which are being moved in their moving direction can be maintained substantially constant by a combination of such a spring and cam shape. Thus, when a slight force is applied by a hand to the movable body or monitor device, the monitor device can be easily moved and, when the force is released, the movable body and monitor device are fixedly located to their new supporting position.
Preferably, in terms of practical use, the article supporting mechanism of a type described above is simple in structure, reduced in the number of components, and reduced in size and weight. However, in the monitor device supporting mechanism described in Patent Document 1, the coil spring serving as the energy storage member is disposed such that an axial direction thereof is substantially perpendicular to the moving direction of the monitor device, and the spring force of the coil spring is used to press the cam follower member positioned at a leading end of an arm member rotatably mounted to the movable body against the cam surface. Not all the reaction force against the cam follower from the cam surface, but only the first component directed in the moving direction of the movable body serves as the force for supporting the monitor device.
Thus, a large spring capable of exhibiting a spring force considerably larger than weights of the movable body and monitor device is required as the energy storage member. In addition, the coil spring is disposed to the front and/or rear of the cam. Consequently, a size of the entire mechanism is enlarged in, especially, a depth direction, and a structure thereof is complicated, making it difficult to achieve a reduction in size and weight.
Further, in the monitor device supporting mechanism described in Patent Document 1, the supporting force for the monitor device is determined by a combination of the spring and cam shape, so that when the monitor device to be supported is changed to one having a different weight, it is necessary to exchange the spring and cam shape or the supporting mechanism itself. Accordingly, it is necessary to prepare a supporting mechanism or a component in accordance with the weight of an article to be supported, thus disadvantageously increasing cost.